AI Tool Tuesday: GPT-5 in Cursor IDE — When AI Coding Gets Scary Good

 

Week 4 of my AI Tool Tuesday series, where I test AI tools in real scenarios so you don’t have to.

What is GPT-5?

OpenAI dropped GPT-5 on August 7, 2025, and it’s not just another incremental update. This is their most advanced model yet, featuring built-in reasoning capabilities that put “expert-level intelligence in everyone’s hands.” But here’s the kicker: instead of testing it through ChatGPT like everyone else, I integrated it directly into Cursor IDE (remember Week 1?) to see how it performs in real development workflows.

The result? Cursor themselves called GPT-5 “the smartest model we’ve used” and “remarkably intelligent, easy to steer, with a personality we haven’t seen in other models.” After spending about a week coding with it, I understand the hype.

My Real-World Test

I put GPT-5 through the ultimate development challenge: building a mobile AI chatbot app with personalized memory and learning capabilities. This wasn’t just a simple chat interface, it required complex architecture, database design, natural language processing, memory management, and mobile-specific optimizations.

The Challenge: Create “Synaptide” — a React Native app featuring:

• Personalized conversation memory that persists across sessions
• User preference learning and adaptation
• Real-time context switching based on conversation history
• Vector database integration for semantic memory retrieval
• Push notifications and reminder abilities for proactive engagement
• Cross-platform compatibility (iOS/Android)

The Result: What typically takes me 2–3 weeks of careful architecture planning, debugging, and iteration was completed in 4 days. GPT-5 didn’t just write code, it designed the entire system architecture, suggested optimal database schemas, and even caught potential memory leaks I would have missed.

What Makes GPT-5 Special in Cursor

Advanced Reasoning: This isn’t just better autocomplete. GPT-5 thinks through problems step-by-step. When I asked it to implement the memory retrieval system, it first analyzed the user experience flow, then designed the data structure, then wrote optimized queries. It was like pair programming with a senior architect.

Context Mastery: GPT-5 understood my entire mobile app structure instantly. When I mentioned “add notification handling,” it automatically integrated with my existing Redux store, followed my component naming patterns, and even suggested UX improvements for notification timing.

Debugging Superpowers: The most impressive moment: GPT-5 identified a subtle race condition in my async memory retrieval that would only appear under heavy load. It explained the issue, provided three potential solutions, and recommended the most scalable approach.

Mobile-Specific Intelligence: Unlike generic AI coding assistants, GPT-5 through Cursor understood mobile development nuances — memory management, battery optimization, platform-specific UI guidelines, and performance considerations for vector database operations on mobile devices.

Natural Problem Solving: I could describe complex features in plain English: “Make the bot remember user preferences but forget sensitive information after 24 hours.” GPT-5 implemented sophisticated data retention policies with automatic cleanup processes.

The Breakthrough Moments

Architectural Thinking: When I hit a performance bottleneck with large conversation histories, GPT-5 suggested implementing a hybrid memory system, recent conversations in local storage, older memories in compressed vector embeddings. Brilliant solution I wouldn’t have thought of.

Error Prevention: Instead of just fixing bugs, GPT-5 prevented them. It suggested input validation patterns, recommended error boundaries for React components, and even flagged potential security vulnerabilities in my authentication flow.

Code Quality: Every suggestion followed best practices. Proper error handling, clean component separation, optimized re-renders, and maintainable code structure. It felt like having a code review expert watching every line.

The Limitations

Over-Engineering Risk: GPT-5’s intelligence can be overwhelming. Sometimes it suggested enterprise-level solutions for simple features. I had to actively guide it toward MVP approaches rather than production-scale architectures.

Resource Requirements: The advanced reasoning comes with computational cost. Cursor with GPT-5 uses noticeably more resources than GPT-4, especially during complex architectural discussions.

Integration Learning Curve: Getting the most from GPT-5 requires more sophisticated prompting. Simple requests get simple responses , you need to engage its reasoning capabilities explicitly.

Cost Considerations: Premium Cursor features + GPT-5 API costs add up quickly for heavy development work. Budget accordingly.

Pricing Reality Check

Cursor Pro ($20/month): Includes GPT-5 access with usage limits GPT-5 API: Varies by usage, significantly more expensive than GPT-4 Total monthly cost for heavy development: $40–80 depending on project complexity

Who Should Use GPT-5 in Cursor?

Perfect for:

• Developers building complex AI/ML applications
• Mobile app developers handling sophisticated user interactions
• Teams needing architectural guidance and code review
• Projects requiring advanced reasoning and problem-solving
• Developers comfortable with premium tool costs

Skip it if:

• You’re building simple CRUD applications
• Budget is extremely tight
• You prefer minimal development environments
• You’re still learning programming fundamentals (might be too advanced)

Comparison to Previous Weeks

GPT-5 in Cursor represents the evolution of Week 1’s review. It’s everything I loved about Cursor’s AI assistance, but with PhD-level reasoning capabilities.

Where GPT-4 in Cursor felt like a smart intern, GPT-5 feels like a senior architect who also happens to code at lightning speed.

My Verdict: 4.6/5 ⭐

GPT-5 in Cursor IDE isn’t just an improvement, it’s a paradigm shift. This is the first AI coding tool that made me feel like I was collaborating with artificial general intelligence rather than using an advanced autocomplete system.

The Good: Expert-level reasoning, architectural thinking, mobile development expertise, proactive problem prevention The Bad: Higher costs, potential over-engineering, resource intensive, steep learning curve The Bottom Line: If you’re building complex applications and can afford the premium, GPT-5 in Cursor is the closest thing to having an AI co-founder.

Try It Yourself

Access GPT-5 through Cursor Pro subscription. Start with a moderately complex project, something that requires architectural decisions, not just simple functions. Ask it to explain its reasoning process. You’ll immediately understand why this feels different from any AI coding tool you’ve used.

Have you tried GPT-5 yet? What’s your experience with the latest AI models?